The invention relates to boring the earth and, more particularly, to an above-ground cleaner for the earth bore that will strip, wipe, scrape, or break off adhering accumulations of mud or cuttings.
The inspiration for the invention includes without limitation the activity of hollow stem auger retraction from being downhole, as in a well bore. The conventional occasion nowadays for wanting to do so is during construction of an environmental monitoring well.
Briefly, groundwater monitoring/remediation wells are bored into the earth. A bore hole is formed by down-feeding a string of hollow stem auger sections. FIG. 1, for example, shows the topmost section of such an auger string (the rest of the string being downhole and out of view). Once the string has bored through to the desired depth, the process then begins of retracting the string.
The purpose behind the auger sections (and consequent string) being hollow is for the down-feeding and construction of a well-casing in the lumen (hollow core) of the auger string. A casing is typically an assembly of PVC pipe sections twisted together by the counterpart internal and external threaded ends thereof. The casing is intentionally undersized relative to the lumen of the hollow stem auger string in which it is inserted. That way, the hollow stem auger string can be withdrawn from the bore, leaving the PVC pipe casing in place. Also, such an undersized casing presents an annular gap between the bored earth and PVC pipe, and this annular gap is eventually backfilled.
To turn to another matter of the prior art, there is another piece of the background to note, which involves the field equipment used by the workers in this industry:—namely, their drilling rigs. Such drilling rigs have two kinds of devices for retracting the hollow stem auger string:—(1) hydraulically-winched cables or lines, in contrast to, (2) hydraulic cylinders.
It might be noted that hydraulically-winched cables and lines, when used to pull free a stuck object, typically include the danger of recoil. Conversely, hydraulic cylinders in the same situation are essentially recoilless. Another thing about hydraulic-cylinder systems is that, they are powerful, and typically outmuscle the power of the hydraulic winches by several times.
A typical drilling rig utilized in the industry might comprise, for example and without limitation, a CME 750 All-terrain vehicle (a rubber tire vehicle) drilling rig of the Central Mine Equipment Company in St. Louis, Mo. This is the carrier/drilling rig combination which is approximately illustrated in several patents of the CME Company, and for more particular disclosure of such carrier/drilling rig features, reference may be had to any of U.S. Pat. Nos. 3,527,309; 3,561,545 and/or 4,638,871—all of which are by C. L. Rassieur. The foregoing patent disclosures are incorporated fully herein by this reference thereto.
Such a carrier/drilling rig has a two-piece tower comprising, in its lower portion, an undergirding upright, and affixed upon that, a removable mast. The crown of the mast might be outfitted with as many as five sheaves. In a five sheave configuration, typically one sheave serves a wireline cable and winch, another serves softlines perhaps pulled by a cathead, and the remaining three would typically serve three cable-and-winch systems for winching up (for example) sections of drill rod.
The wireline cable and softline-cathead system are not pertinent to the present invention. Typically the wireline cable system reels up a wire relatively fast but with a weak hoist. A weak hoist, for instance, is only able to exert 900 pounds or ˜400 kg of force or so, which is fine for rock-coring but is otherwise weak. The cathead is like a capstan on a ship, except oriented on a horizontal turning axis, and can winch in by means of one or two loops not only softlines but also cables or chains as well. It too is typically a weak system.
Stronger still are the (three or so) cable-and-winch systems. It is typical to equip the drilling rig with winches rated between about 1,800 or to 3,200 pounds (˜700 to ˜1,400 kg). It is also known to include at least one cable-and-winch system as a main one for fishing stuck objects and the like, and provide it with a retraction-force rating as high 10,000 pounds (˜4,500 kg). Again, these three cable-and-winch systems are designed for, among other end uses, lifting up sections of drill rod. The height of the tower to the crown of the mast is typically something greater than twenty feet (˜6 m) since that is a standard length of sections of drill rod. The above-ground height of the sheaves for the CME 750 ATV is about twenty-seven and a-half feet (˜8⅓ m), which means that workers can hoist the twenty-foot (˜6 m) rods with clearance to spare. When the CME 750 ATV is equipped with three such hoists (ie., cable-and-winch systems), workers can pull sixty feet of rods without having to lay any down on the ground or on the deck.
The upright (again, the lower part of the tower, which undergirds the upper part, the detachable mast) comprises legs and a standing rotary drive shaft (such as a kelly bar, or sometimes a square bar). The standing rotary drive bar typically has a lower end anchored in a main rotary drive and an upper end held in a bearing. The legs carry between (or among) themselves a traveling rotary table. Drive input to the rotary drive table is received from the standing rotary drive shaft as the traveling rotary table transits up and down the standing rotary drive shaft. The drill drive is typically a pair of serially-suspended links interconnected by a U-joint.
The hydraulic vertical drive system for cycling the traveling rotary drive table between feed (“pulldown”) and retraction strokes typically comprises hydraulic cylinders. Theses hydraulic cylinders serve double-duty as the legs for the tower's upright. The main rotary drive and the hydraulic vertical drive system are typically the strongest systems on the carrier/drilling rig. That is, the main rotary drive might deliver 10,000 ft-lbs (˜13,5000 Nm) of rotary torque. The hydraulic vertical drive system can typically deliver a feed (“pulldown”) force in excess of the weight of the vehicle, or something on the order of 20,000 pounds (˜9,000 kg).
The outstanding feature of the hydraulic vertical drive system is the retraction force it can develop:—which is 30,000 pounds (˜13,600 kg) for the CME 750 ATV, and then 40,000 pounds (˜18,000 kg) being no problem for other models.
As an aside, another aspect of the hydraulic vertical drive system is that, its drive stroke is only about five and a-half feet (˜1⅔ m). Unlike drill rod sections (which measure a standard twenty feet or six meters in length), hollow stem auger section conventionally measure a standard five feet (˜1½ m) in length. Therefore, the hydraulic vertical drive system's drive stroke of about five and a-half feet (˜1⅔ m) is more than sufficient to provide clearance for withdrawal of hollow stem auger sections.
More importantly, the hydraulic vertical drive system has no cables which can stretch (nor chains which need lubrication). Better yet, the hydraulic vertical drive system is substantially recoilless. When feeding down or retracting up against a stuck hollow stem auger string, as soon as the sticking force is overcome, the hydraulic vertical drive system does not recoil. In contrast, if a winch and cables were being used, cables stretch and the stuck hollow stem auger string (if being retracted up) can let fly after being unstuck (or after being torn apart). The cables might whips (chains would do the same) and so on. Moreover, cables can snap (so can chains). Accordingly, the hydraulic vertical drive system is better at giving precise control over the force applied to downhole tools or objects.
Arguably most significant of all is that, its brute power aside and in spite of being the most powerful system on the carrier/drill rig, the hydraulic vertical drive system is probably the safest.
Now let's return the discussion back to retracting the auger string. Hollow stem auger sections interconnect with each other by their top and bottom collars. The topmost hollow stem auger section is down fed into the bore hole by a drive cap attached to the drill drive (or extension thereof) of the drill rig. FIGS. 1 through 3 show a drive cap and the top collar of the a hollow stem auger section.
When boring a well, workers usually have a mess to deal with, and understandably so, since it is a messy process in a messy environment. The auger sections typically withdraw with adhering accumulations of mud or cuttings caked inside their flutes.
These accumulations of mud or cuttings, if left to dry, harden as hard as sun-baked bricks, which is no surprise since basically it is the same starting material as used in sun-baked bricks. It would be desirable to clean the auger sections of such accumulations of mud or cuttings as soon as practicable after withdrawal from the bore hole, while fresh. That is, fresh accumulations of mud or cuttings are easier to clean off than if left to dry. Dried and hardened material is considerably more difficult to get to release. Also, another reason for wiping the auger sections as soon as practicable is that, such accumulations of mud or cuttings are tremendously heavy. Hence the hoisting and handling of the hollow stem auger sections would be considerably eased if unloaded of such material.
What is needed is a solution for this problem.
A number of additional features and objects will be apparent in connection with the following discussion of the preferred embodiments and examples with reference to the drawings.